Tuning mechanism for radio apparatus



May 2, 1939. L. F. CURTIS ET AL TUNING MECHANISM FOR RADIO APPARATUS Filed July 24, 1957 6 Shee ts-Sheet 1 I \QJQ v I Q; 3 o O 3 7 Q j 6 0 I: Es g Q5} 9 o /7 4 Q 0 7/ Q $Q J m7 b INVENTORS AfJl/f amr/J ,6 f7? 605 A QM/l ATTORNEY.

May 2, 1939. L. F. CURTIS ET AL TUNING MECHANISM FOR RADIO APPARATUS Filed July 24, 1937 '6 Sheets-Sheet 2 O .1???- 4. j Q

\ fl k O M //i 1/ y w if 1; /77 1/ 7/1 w Z5 IN VENTORS ATTORNEY.

May 2, 1939. L. F. CURTIS ET AL TUNING MECHANISM FOR RADIO APPARATUS Filed July 24, 1937 e Sheets-Sheet 5 IN VENTORS BY ff I I @2444 ATTORNEY.

y 1939- L. F. cuRTls ET AL 2,156,679

TUNING MECHANISM FOR RADIO APPARATUS Filed July 24, 1937 6 Sheets-Sheet 4 ljya. if

INVENTORS ATTORNEY.

y 1939- L. F. CURTIS ET AL 2,156,679

TUNING MECHANISM FOR RADIO APPARATUS Filed July 24, 1957 e Sheets-Sheet 5 ATTORNEY.

y 1939- L. F. CURTIS ET AL 2,156,579

TUNING MECHANISM FOR RADIO APPARATUS Filed July 24, 1937 6 Sheets-Sheet 6 INVENTORS 155105 f. CW/f'T/J' 9E F/f/l/V/f 5. C05

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Patented May}, 1939' V PATENT OFFICE aroma nonamsu ron. aamo mans-ms mus nouns-m1 Frank s. oe,

toAmerlcan Bosch Corpora- Masa, a corporation or New Ila-s nlignorl tion. Springfiel York Application In]: 24. 1931, Serial No. 155,388 4' claim; ((11. ass-4o) This inventionrelates to improvements in radio tuning devices of, the automatic type which may be either manually or electrically operated.

It is among the objects of this invention to provide a tuning device in which certain selected stations may be tuned in by merely pressing a button or by pressure upon such a button combined with a movement of the dial mechanism.

It is a further object of this invention to combine. such an automatic tuning mechanism with means permitting manual tuning in a conventional manner when so desired and for also combining such mechanism with means for controlling automatic frequency control circuits which will insure the accuracy of the tuning in either case, and furthermore with means for muting the loud speaker during tuning operations.

A further object of the invention is to provide simplified mechanism for selecting one of a plurality of stations and for releasing the control of any previously selected station, when the button controlling some other station is depressed.

The invention resides in the novel construction, combination and arrangement of parts as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiments of the herein disclosed invention may be made as come within the scope of the claims.

The above and other objects and features of the invention will be more fully set forth in the following description taken in conjunction with embodiments of the invention which will enable those skilled in the art to apply the same to either motor driven or manually driven automatic tuners.

In the drawings, Fig. 1 is a front elevation of a motor driven automatic tuning device embodying the invention with parts broken away to show internal structure; Fig. 2 is a detail of the control unit; Fig. 3 is a bottom plan view of the control unit; Fig. 4 is a plan view of the device shown in Fig. 1 with the panel scale of the station selector unit removed; Fig. 5 is a bottom plan view of the device shown in Fig. 1; Fig. 6 shows, on an enlarged scale, a section taken on the line 6-6 of Fig. l, with parts in side elevation; Fig. 7 is a detail showing the electrical connections betweena gate switch and the slip rings and brushes for efiecting an electrical connection therewith; Fig. 8 is a detail of the slip rings and brushes; Fig. 9 is a detail showing a motor switch in closed position; Fig. 10 is a detail showing the same switch in open position; Fig. 11 is a detail of a manual control switch; Fig. 12 is a wiring diagram of the tuning mechanism shown in Fig. 1; Fig. 13 is a front elevation of a manually driven automatic tuning device embodying the invention; Fig. 14 shows, on an enlarged scale, a vertical axialsection with parts in side elevation,

of the device shown in Fig. 13; and Fig. 15 is a detail of the latch plate of the device shown in 3 Fig. 13.

of push buttons '3 circularly disposed about a central tuning knob 4. The push buttons 3 pro- 'ject through a cover 5 having a central opening for the tuning shaft Ii, and also having circumferentlal openings I through which the push rods 8 project. The rods 8 are provided with cam surfaces 9 intermediate their ends and grooved guide members Illon the lower ends thereof mounted for reciprocative but not rotative movemerit through openings II in a back plate I2 of the control unit. Stop member levers l3 carry ing stop members I4 are afilxed to the extreme ends of the rods 8 below the guide members I0. Springs l5, acting at one end upon collars I6 afiixed to the rods 8 at a point below' the cams 9, act against the back plate I2 to maintain the rods 8 in an outward position while the levers I3 prevent the guide members III from passing outwardly through the openings I I in the back plate I2.

A latch plate I 'I is mounted upon and maintained in spaced parallel relation to the back plate l2 by means of a central spacer bushing I8. The latch plate I! is provided with cut away portions I 9 leaving radially projecting fingers 20. Slots 2|, only one of which appears in Fig. 1, cut through the latch plate II near its outer circumference, and accommodate springs 22 attached at one end to the latch plate and at their opposite ends to spring studs 23 projecting outwardly from the back plate I2 through the slots 2I. The springs 22 tend to rotate the latch plate upon the bushing I8 in the direction of the arrow and maintain the fingers against the button rods 8 which project through the cut away portions IS, the contact of the fingers with the rods being made at points adjacent the cam surfaces 9. A plurality of guide studs 24 projecting outwardly from the back plate l2 are provided with grooves 25 near their outer ends. The guide studs are so positioned relative to the outer ends of the latch fingers 20 that the latch plate is held rigidly against lateral motion relative to the back plate I2 but permitted an angular motion relatively thereto. The station selector control unit above described is supported by a plurality of studs 21 projecting perpendicularly from a base plate 28 which is riveted to a bracket member 29 having upturned side portions 30 with outwardly extending flanges 3| to which the scale panel I is attached by means of button clips 82.

The tuning shaft 8 projects through the spacer bushing I8. and through a second spacing bushing 34 supportedin an opening 35 in the base plate 28. A disk 38 coaxial with and rotatably mounted relatively to the tuning shaft 5 lies immediately behind and spaced from the back plate I2 of the control unit. iecting rearwardly from disk 35 supports slip rings 31 suitably insulated therefrom for effecting certain electrical connections hereinafter more particularly described. The disk 35 is provided with a large cruciform opening 38 through which a gate switch 39 projects. The gate switch 39 comprises a pair of flat springs 40, each of which are riveted at one end to the disk 35 and their free ends are riveted to latch members 4I, each of which has a portion projecting outwardly through the opening 38 and providing surfaces slightly inclined to the plane of the disk 35. Attached to the back face of this disk, at a point adjacent the opening 38, is a switch 42 having an outwardly extending portion 43 which projects between the members 4|. Contact members 44 project through an opening 45 in the upwardly extending shaft I2 forrotation with the gear 14.

portion 43 and rest upon insulating strips 45 riveted to the end of downwardly projecting portions of the members 4!. Each of the stops I4 on the levers I3 are adapted upon depression thereof to enter the gap between the two latch members 4| and contact the upwardly projecting portion 43 of the switch 42. The lever indicated at I3 however carries no stop member I4 but merely projects a suiiicient distance to overlie a stationary switch 41, the details of which may be seen in Fig. 11. This switch comprises a plurality of spaced metallic strips 48 carrying suitable contact points with alternate strips projecting somewhat beyond the others and the projecting ends rigidly connected through insulating members 49. The projecting portion of the switch lies in the path of lever I3 and is contacted by the downward motion thereof.

The disk 38 carries a stud 50 rigidly attached thereto and projecting rearwardly therefrom and a second stud 5i angularly spaced from the stud 50 and adjustable circumferentially of the disk 38 in a circumferential slot 52. An angle bracket 54 is riveted to the base plate 28 and carries a reversing switch 55, a shaft 55 of which carries a lever 51 rigidly held thereto by means of a set screw 58. The lever 51 has its free end bent inwardly and extended beneath the disk 35 in a position to be contacted by the projecting studs 50 and 5|.

An opening 50 is provided in the base plate 28 and a driving motor 5| is mounted to project therethrough, being held in position by tie rods 52 which extend through clamping yokes 53 on the rear face of the plate 28. The shaft 55 of the motor projects rearwardly of the plate 28 and carries a pulley wheel 56. The tuning shaft 5 carries a pulley 58 rigidly secured to the end thereof which projects rearyvardly of the plate 28 by means of washer 59 and lock nut 10. A small pinion II is positioned upon the tuning shaft adjacent the pulley 58 and is rigidly secured thereto for rotation therewith. An idler shaft I2 is mounted on a bracket I3 riveted to the back face of the plate 28 and the shaft carries a large gear I4 meshing with the pinion II. A large pinion I5 and a small pinion 15 are mounted on the idler The large pinion 15 meshes with a gear 11 coaxial with but mounted for relative rotation to the tuning shaft 5. The gear-11 is coupled with the disk 35 by A collar 31 attached to and promeans of a sleeve I9. The smaller pinion 18 on the idler shaft meshes with a gear I9 larger than the gear 11 but mounted coaxial therewith and for rotation relative thereto. A pointer arm carrying a pointer 8| is rigidly connected with .the gear 19. The pinions l5 and I5 and the gears 11 and I9 are of such relative sizes that the angular rotation of the disk 35-is twice as great but in the same direction as the angular rotation of the pointer arm 80. A stud 82 projecting rearwardly from the pointer arm- 80 is adapted to cooperate with a forked arm 83 for actuating the shaft of a tuning condenser gang not shown.

The plate 28 is provided with a cut out portion 84 to accommodate a three way switch 85 for the wave band selector circuits. The switch may be manually actuated by means of a knob 85 upon shaft 81. Intermediate the ends of the shaft 81 is a pulley 88 having one end of a cord 89 attached thereto. The cord 89 is suitably guided through a groove 90in a stud 9i and is wrapped about a spool 92 supported from the plate 20 on a bracket 93. The spool 92 carries a suitable band indicator 94. The free end of the cord 89 is attached to one end of a spring 95, the opposite end of which is hooked to the bracket 29. The band indicator is visible through an oblong slit 95 in the panel I and markings thereon register with one end of the panel scales in accordance with the setting of-the band indicator switch.

to one end of a cord II which cord is suitablyguided in a groove I02 on a stud I03. The cord is thence wrapped about a spool I04 supported by a bracket I05 and the free end of the cord is attached to one end of a'tension spring I05, the opposite end of which is hooked to the bracket 29. The spool I04 carries an on and o indicator visible through an oblong opening I01 in the panel I to indicate to the operator whether the automatic frequency control switch is on or off. Below the pulley I 00 on the shaft 95 is a lever I08 rigidly fixed to the shaft 98. The opposite end of the lever I08 is pivotally connected to a connecting rod H0, which extends to an arm III of a bell crank H2. The shaft II3 of the bell crank H2 is journalied in bushing II4 which extends through an opening in the plate 28 positioned near the motor 5|. A second arm I I5 of the bell crank H2 is connected to the shaft H3 and the free end of the arm H5 carries a stud III upon which a tension pulley H8 is rotatably mounted in the plane of the motor pulley 55. The arrangement of these parts is such that the belt 9 befrequency control switch is in "oif position.

Thus when this switch is oil, the tension pulley will be in the position shown in dotted lines in Fig. 5, but when the automatic frequency control switch is on, the tension pulley I I8 is in the position shown in full lines in this figure and the motor is effective to drive the tuning shaft pulley 58 and the motor cannot drive the tuning shaft pulley when the automatic frequency control switch is in off position.

In the operation of the form above described, when one of the push buttons 3, but not the one marked 3', is depressed, the switch 39 which controls the motor 5i is closed and if the automatic i'requency control switch is in "on position as above described themotor drives the pulley 33 on the tuning shaft at a that of the motor. This motion is directly trans- .mitted to the tuning shaft 3 to which the pulley 03 is directly connected and the motion is also transmitted at a greatly reduced speed through the pinion II on the tuning shaft and the gear the pointer arm I4 on the idler shaft to the two gears II and I8 by means of pinions'l! and II. The ratioof these gears is such that the large pinion I6 drives the smaller gear 11 at twice the speed which the small pinion It drives the large gear I3. Thus which rotates with the large gear 13 moves the pointer 3| through an arc of 180 degrees while the disk 3 is moved through an arc of 360 degrees by the sleeve I3 connected with the small gear 11. The gate switch 33 is thus moved through the n are up to 360 degrees required for the stop I4 of whichever of the push rods that has been depressed to slip into the gate switch 33 in which position the motor circuit will again be opened and the disk 30 locked in the stop position. One of the fingers 20 of the latch plate I! having been locked in a groove above the cam surface 3, the removal of pressure upon the button 3 does not release the button and the gate remains locked at the station indicated. If the selected station happens to lie at the left of the pointer II when the station has been selected by the depression of its corresponding button, the disk 36 carrying the gate switch 33 may be rotated to the right by motor 6|. However, after rotation of the disk to the right to the limit permitted by the pointer arm 30 coming to the extreme end of the dial, one of the studs 53 or SI will trip the reverse switch to reverse the motor causing the same to rotate the disk 30 to the left, thus insuring that the gate switch will, during the course of its rotation in this direction pass under the depressed stop member permitting the same to be locked in the desired position without action upon the part of the operator other than the original depression of the desired button. The tuning arm is thus stopped at apoint very close to the correct position and the automatic frequency control circuit which is necessarily on at this time insures tuning accuracy. The depression of any of the other buttons causes the latch plate H to be rotated slightly by the corresponding cam surface in a direction opposite to that in which it.is biased by the springs 22. The rotation in this direction thus removes one of the fingers 20 from any of the depressions in the push rods 3 with which it might have been engaged and as the cam 3 of any newly depressed rod forces the latch plateto the left the previously depressed rod will be released. Immediately thereafter as a finger 20 of the latch plate I! rides over the cam surface 3 and sinks into the depression the newly depressed rod will be latched in the depressed position.

If the push button 3' is depressed any previously depressed button is released by the action of the associated cam 9 upon the latch plate I1 as described in connection with the operation of the buttons 3. However, the motor does not begin to rotate because the lever I3 associated with button 3' immediately contacts the projecting portion of the switch 41 to open the motor circuit. The button 3', therefore, corresponds'to no call station but acts as a release of the automatic control so that the set may then be tuned manually by rotation of the tuning shaft through slow speed relative to the knob In practice the button 3' is colored differently from the other push buttons.

The electrical circuits associated with the above mentioned parts are shown in Fig. 12, in which it will be seen that current supplied from a trans-.

former I20 flows by way of the reversing switch to the motor 6|. cludes a field coil I22 of the motor leads by way of one of the sets of contacts of switch 41 and thence through one of the sets of contacts of switch 42 to the ground. An A. F. C. bias circuit also leads to a second set of contacts of the stationary switch 41 and thence through a second set of contacts of the switch 42 to the ground. The loud speaker circuit, indicated at I23 and supplied with audio frequency current by transformer I24, is provided with a lead I25 which connects to a third pair of contacts of switch 41 and thence to a third set of contacts'of switch 42. From this it will be seen that when switch A field circuit I2I which in- 41 is closed, lever I3 being out of'contact with lever I3 be in depressed position, all three of the sets of contacts of the three circuits de-, scribed will be opened. The manually adjustable A. F. C. switch may, however, be closed if desired.

Referring to Figs. 13,-15 it will be observed that this modified form of the device is provided with a front panel and scale similar in construction to that of the form previously described and the structure is in general similar except that the motor drive being eliminated the construction is modified in certain respects to facilitate the manual actuation of the selective control unit. In this instance the control unit indicated at I3I comprises a cover member I32 having a plurality of openings I33 arranged at closely spaced intervals near the outer circumference thereof and through which buttonsv I34 of push rods I36 may be actuated. The cover I32 is provided with a central opening I36 through which a tuning shaft I31 carrying the knob I33 projects. The cover is supported by tie rods I39 which extend from a back plate I40 through a casing I which is rigidly secured to the back plate by means of nuts I42 upon the tie rods I39. The tie rods project outwardly for a sufllcient distance to provide a support for the cover I32 which maintains it in spaced relation to the casing I,

screws I43 being provided for securing the cover ends, immediately beyond the guide members I44,.

push rods carry levers I46 having stop members I41 on the outer ends thereof. The push,rods are provided with collars I48 on the intermediate portion thereof and springs I49 acting at one end against the collars I48 and at the opposite end upon the back plate I40 maintain the push rods in a normally outward position with the levers I46 pressed against the rear of the back plate I40. The entire control unit is' rotatably mounted as a body upon a collar I50 rigidly secured to a base plate I5I which collar maintains the unit in spaced relation from but relatively movable to said base plate. The base plate I5I is provided with a cruciform opening I52, and leaf springs I63 having ends rigidly attached to I56 which is mounted upon an idler shaft I51 carried by a bracket I68 supported from the base The idler shaft carries a relatively plate ISL large pinion I58 and a smaller pinion I60 which rotate with the idler gear I56 and which mesh respectively with a small gear I6I and a large gear I62 which are mounted concentric with the tuning shaft for relative motion'thereto and for relative motion with each other. The small gear Iii is rigidly connected with a sleeve I63'which projects through the collar I50 and is rigidly connected at its opposite end with the control unit I3I. The larger gear I6! is connected to a sleeve I63 rotatably mounted upon sleeve I63 within the collar I53 and a pointer arm I64 which carries a dial pointer I65 and a stud I66 for actuaflng an arm upon a shaft of a variable condenser in a manner similar to that described in connection with the form previously discussed is mounted upon the sleeve I63 for rotation therewith. The base plate II is riveted to a bracket I61 which provides a panel support in the manner noted in connection with the previously described In each of the forms above described, and as more particularly shown in Fig. 14, the push rods I35 are of two part construction to permit the angular adjustment of the stop levers I46. Refen-log to this figure the outer portion of the push rod I35 consists of a sleeve I10, one end of which accommodatm the snap button I34 and the opposite and of which receives a stem "I which is externally screw threaded to correspond with internal screw threads within the sleeve. A groove I12 is provided in the outer end of the stem HI and the opposite end of the stem is provided with a conical portion I13 which conforms to an internal surface of the guide member I44 so that upon removal of the snap button I34 a screw driver may be inserted within the sleeve I to rotate the stem III and thus adjust the angular position of the lever I46. The position of the stop member I41 may thus be adjusted to any dial position between that of its corresponding push button and that of the next preceding or succeeding push button. Since each of the levers I46 may thus be adjusted any point on the dial may be selected by the use of the push button corresponding approximately to the desired posilion and the adjustment of the corresponding lever I46 to the exact position.

The operation of the form shown in Figs. 13-15 is in general similar to the operation of the form previously described, except that upon depression of one of the buttons 34 the operator must rotate the control unit I 3i until the stop member I41 of the depressed button enters the gap between the two latch members I54 which holds the control unit from further rotation. The gearing between the control unit and the pointer arm I64 is such that as the operator rotates the controlunit through an arc of 360 degrees the pointer is moved through an arc of 180 degrees. Thus any point on the dial corresponding to any desired station is within the range of adjustability of one or more of the stop members I41. In this form it will be observed that no switch mechanism need be associated with the latch members I54,the depression of the stop member merely-acting to pression of the stop member merely acting to position the dial poin er at a predetermined point upon the dial.

Having thus described the invention, what is claimed is:

1. In an automatic tuning device for radio receivers, a central shaft, a plurality of push-rods disposed about said tuning shaft, stop members associated with said push rods, and a pair of spring pressed latch members having adjacent portions spaced to form a slot extending radially of said tuning shaft, said push rods and said latch members being relatively movable, and a switch member projecting into said slot for actuation by said stop members.

2. In an automatic tuning device for radio receivers; a tuning shaft; and'a selective station control unit comprising a plurality of push rods, stop members associated with said push rods, adjustable angularly about the axis thereof from the front of said tuning device, a gate mechanism including a pair of oppositely disposed spring pressed latch members, a switch member positioned between said latch members for actuation by said stop members, said control unit and said mechanism being mounted for relative motion,

prevent further relative motion at a predetermined position of said tuning shaft.

3. In an automatic tuning device for radio receivers, a tuning shaft,.an electric motor, a belt for transmitting motion from the motor to said tuning shaft, a tension pulley movable to apply tension to said belt, me us for stopping said mosaid tension pulley to remove the tension upon said belt to prevent operation of said tuning shaft by said motor when said automatic frequency control switch is in off position.

4. In an automatic tuning device for radio receivers, a tuning shaft, a selective station control unit comprising a plurality of push rods disposed about said tuning shaft and mounted for lon gitudinal movement, springs biasing said rods toward outward position, stop members connected to the inner ends of said rods, cams on the indepression of one of said rods first causes oscillation of said latch plate in one direction against the action of said resilient means to remove said fingers from contact with any previously depressed rod and to subsequently be returned by said resilient means into a depressed portion of said cam to lock said rod in depressed position.

LESLIE F. CURTIS. FRANK S. COE. 

